ROME — An unknown number of American citizens are believed to be among a group of hostages captured by militants at a gas facility in an eastern Algerian town near the Libyan border, U.S. Defense Secretary Leon Panetta said.

“I do not have firm information as to how many hostages are involved,” Panetta said during a Jan. 16 meeting with reporters in Rome. “We do believe that there are Americans involved here.”

U.S. officials are “in consultations” with the Algerian and British governments to determine the events leading up to the capture of the foreign nationals and their current state.

In addition to Americans, news reports from the region said British, Norwegian and Japanese citizens were also among the hostages.

“We’re continuing to review the situation to determine exactly what happened,” said Panetta, who is in the midst of a weeklong trip to meet with defense officials across Europe.

Panetta — who received a briefing on the hostage situation shortly before a Jan. 16 meeting with reporters at a scheduled press conference at the U.S. Embassy in Rome — condemned the incident and said it appears to be a “terrorist act.”

“I want to assure the American people that the United States will take all necessary and proper steps that are required to deal with this situation,” he said.

The defense secretary could not confirm whether the Algeria incident is tied to France’s recent engagement with al-Qaida fighters in Mali.